General Library

Part of the auditory and vestibular systems, it detects sound and helps to maintain balance. It is composed of three main parts: the outer ear (pinna, ear canal, surface of ear drum), middle ear, and inner ear (cochlea, vestibule, and semicircular canals).

The presence of extra amounts of fluid in the intercellular tissue space; swelling. It may be localized due to venous or lymphatic obstruction or increased vascular permeability or it could be systemic due to heart failure or kidneydisease.

A medical instrument used to assess cardiac function by measuringthe electrical activity of the heart. With each heartbeat, an electrical signal spreads from the top of the heart to the bottom. As it travels, the signal causes the heart to contract and pump blood and sets the rhythm of the heartbeat. The process repeats with each new heartbeat. ECG detects these signals with electrodes that are placed on the body. It shows how fast the heart is beating, whether the rhythm of the heartbeat is steady or irregular, and the strength and timing of electrical signals as they pass through each part of the heart.

A self-propagating wave in space with electric and magnetic components. These components oscillate at right angles to each other and to the direction of propagation, and are in phase with each other. Electromagnetic radiation is classified into types according to the frequency of the wave. These types include, in order of increasing frequency: radio waves, microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays. EM radiation carries energy and momentum, which may be imparted when it interacts with matter. The waves with the higher frequency have shorter wavelengths and higher energy.